Fermentation, bioproducts produced

Table 1 Some bioproducts produced by fermentation and downstream processing steps used in their recovery and purification...

A wide variety of products can be produced by fermentation. In some cases the microorganism itself is the product, for example, in the manufacturing of active dry yeast (ADY). Well-known pharmaceutical fermentation products are insulin and penicillin G. Fermentation processes are also used to produce various commodity bioproducts like organic and amino acids, polysaccharides, lipids, chemical compounds like isoprene (Whited et al., 2010), 1,3-propanediol (Nakamura and Whited, 2003), RNA, DNA, enzymes, and other proteins. The large variety of commodity bioproducts produced by fermentation requires an equally large variety of different methods to separate and purify them. Compared to fermentation processes, where usually one unit, the fermenter vessel, is used, several different steps and unit operations are necessary to achieve purification and formulation of bioproducts. 

First, the advances in molecular biology will enable a much broader range of bioproducts, produced via fermentation by computer-designed cells and microorganisms, perfectly tuned to the continuously changing environment in large-scale bioreactors, with maximum carbon and energy conversion efficiencies. 

Approximately 89 million metric t of organic chemicals and lubricants, the majority of which are fossil based, are produced annually in the United States. The development of new industrial bioproducts, for production in standalone facilities or biorefineries, has the potential to reduce our dependence on imported oil and improve energy security. Advances in biotechnology are enabling the optimization of feedstock composition and agronomic characteristics and the development of new and improved fermentation organisms for conversion of biomass to new end products or intermediates. This article reviews recent biotechnology efforts to develop new industrial bioproducts and improve renewable feedstocks and key market opportunities. 

In recent years, BASF AG, Ludwigshafen, and Omnigene Bioproducts, Cambridge, MA, USA, have developed a novel fermentation process for preparation of D-pantothenate with Bacillus [8]. Bacillus subtilis is inherently capable of producing... 

Some bioproducts are derived from fermentation by living organisms but immobilized enzymes can also catalyze a biotransformation. If the product is extracellular, then the initial steps of recovery include removal of the cells and other particulate matters from the broth. If the product is intracellular, it would be necessary to lyse the cells to release the product into the broth. The cell debris is then separated before the product is recovered from the broth. In certain cases, proteins produced as IBs need to be solubilized and the proteins renatured before further recovery steps. In the case of biotransformed products, the immobilized cells or enzymes and their support need to be removed initially. 

A classical example for a biobased polymer, which can be made from renewable bioproducts, is polyethylene (PE), which is nowadays produced exclusively by the catalyzed polymerization of ethylene coming directly from the steam cracker, a 100% petrochemical process. Ethylene, however, can also be produced via ethanol coming from glucose fermentation. This is a typical bio process. 

An example of a commodity bioproduct everybody has probably encountered is ADY. In this case, the cells are the product. The downstream processing for ADY can consist of several washing steps and concentration by centrifugation. The washing steps remove the fermentation media from the yeast cells. The yeast cream obtained by centrifugation is further concentrated using a filter-press to produce a yeast cake. Extrusion and drying of the yeast cake yields the final ADY product. 

In a joint venture with Tate and Lyle PLC, known as DuPont Tate Lyle BioProducts LLC, DuPont plans to produce 1,3-propanediol (PDO) using their proprietary fermentation and purification process based on corn-derived glucose. Sample quantities of the biobased PDO are currently produced at a pilot plant in Decatur, Illinois and beginning in 2006, commercial-scale quantities will be produced at a manufacturing facility in Loudon, Tennessee (10). 

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